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1. Field of the Invention
The present invention generally relates to material handling systems and methods. More specifically, this invention relates to apparatus and a related method for supporting, uncoiling, dekinking, and feeding coiled material.
2. Description of the Related Art
Material handling systems are used in various applications to unwind a coil of web material and convey the web material to a downstream machine. Such applications include but are not limited to wire feeding, paper feeding, sheet metal feeding, and the like. The typical coil is wound from a discrete length of material having a leading end that terminates an outside diameter of the coil and a trailing end that terminates an inside diameter of the coil.
Sheet metal uncoilers of the prior art are typically included as one piece of a material handling system amongst others including a threading mechanism, a straightener/feeder machine, and ultimately a metalworking machine such as a press. The typical uncoiler includes a cradle or reel that supports the coil of material.
A cradle usually includes a base frame structure having a pair of spaced apart and parallel support rollers mounted thereto. The rollers support the outside diameter of the coil of web material such that the coil rests freely thereon. A pair of opposed sidewalls are typically mounted to the base frame structure to restrain the sides of the coil and thus prevent xe2x80x9ctelescopingxe2x80x9d of the coil. The sidewalls are usually laterally adjustable towards and away from one another to accommodate various widths of coils to be loaded to the cradle.
One type of reel uncoiler includes a base frame structure having a single support shaft or roller that is mounted to the base frame structure and that supports the coil through the inside diameter thereof. Another type of reel includes a base frame structure having opposed adjustable arms that terminate in chucks for supporting the inside diameter of a coil at the sides thereof. Both types of reels typically include a drive roll that engages the outside diameter of the coil for rotating the coil to wind or unwind the coil.
There are numerous problems with both types of uncoiler systems of the prior art. Cradle-type uncoilers suffer from three significant disadvantages. First, if the coil is not positioned correctly when it is initially loaded to a stationary cradle, it can be very difficult to recenter, especially if the coil is very heavy. Second, the side edges of the coil often get bound up or damaged between the side plates when the coil xe2x80x9ctelescopesxe2x80x9d. Specifically, the side plates shave slivers from the side edges of the coil and the slivers tend to accumulate in downstream stamping dies, resulting in damage thereto. Third, coils are supported only by line contact atop the cradle support rollers and the enormous weight and light gauge of some coils makes it difficult to run quality material. Sheet metal thickness for automotive body panels has decreased drastically over the last several decades, from approximately 0.039xe2x80x3 to about 0.023xe2x80x3. Heavy coils of this lighter gauge material can experience more than 1,000 psi on the outside diameter of the material. This extremely high pressure tends to plastically displace material out at the edges of the coil. This is because the coils are more rigidly supported at their sides and are more forgivingly supported at the center due to the natural sag of a support roll at the center. This phenomenon is known as xe2x80x9cwavy edgexe2x80x9d and tends to adversely affect downstream die operations. A cradle-type uncoiler is typified by U.S. Pat. No. 4,487,045 to Lehmann et al.
As a solution to the above-mentioned problems with cradle-type uncoilers, reel-type uncoilers have been developed, but have three significant limitations of their own. First, a typical reel uncoiler usually requires a separate straightener-feeder system, other additional equipment, and a take-up loop of the material to achieve proper payoff of the material, thereby adding substantial length to the line between the coil and the press. This limitation is typified by U.S. Pat. No. 4,953,808 to Craycraft and U.S. Pat. No. 5,651,511 to Crowley et al., wherein space consuming take-up loops are evident. Second, it is difficult to thread heavy gauge material with the coil supported at a fixed height. Use of different size coils having various outside diameters makes it impossible to use a typical fixed length threader device since the leading end of the material is at a significantly different location for each varying size of coil diameter. Third, existing reel uncoilers are sometimes inadequate to prevent a coil from xe2x80x9cwatchspringingxe2x80x9d once a restraining band is released from the coil. For example, neither the Craycraft nor Crowley et al. references make even a passing mention about alleviating the watchspringing problem.
Moreover, neither the cradle-type nor reel-type uncoilers of the prior art have provided an adequate mechanism for dekinking the trailing edge of a coil of heavy gauge material. The trailing edge of a coil of heavy gauge material is often kinked into a xe2x80x9ccoil end bendxe2x80x9d that is either produced from steel mill equipment when initially winding the coil or from a rewind mandrel clamp when loading the coil to the mandrel. U.S. Pat. No. 4,487,045 to Lehmann et al. teaches use of a threader bar roller in combination with a fixed removal roller to decurl a trailing end of a coil roll. This combination enables easier acceptance of the material by input rolls of a straightener and precludes a doubled over coil thickness of material from being rolled over, thereby avoiding substantial damage and downtime to the downstream straightener and press. Unfortunately, however, the Lehmann et al. combination is not effective for dekinking heavy gauge material since the rollers do not cooperate closely under forces sufficient to dekink such material.
Rather than dekinking a trailing edge of coiled sheet stock, many prior art devices cut the ends off of a length of stock at the beginning and end of each coil. U.S. Pat. No. 4,344,605 to Ganseuer et al. teaches use of just such a device. Ganseuer et al. disclose a fixed support structure having a horizontal support cradle thereon for holding a coil. The support structure includes a gap spaced downwardly from the cradle, through which material from the coil passes. A cutting torch or shear blades are translatably fixed to a portion of the support structure beneath the gap, such that the torch traverses across the path of the material to cut it off. Such a system wastes valuable coiled material, results in scrap and a messy work environment, and is a relatively high maintenance design.
U.S. Pat. No. 4,070,891 to Stretten teaches an apparatus for peeling the leading end of coiled sheet metal and for debending and straightening a trailing end of the sheet metal. FIG. 1 thereof illustrates the typical material handling system of the prior art requiring a space-consuming loop. A debender is positioned just downstream of a cradle-type uncoiler. The debender includes a lower forming die and a complementary upper forming die that are aligned with guideposts. Sheet metal from the coil flows between the upper and lower dies. A pair of pneumatic cylinders drive the upper die down toward the lower die along the guideposts. In operation, a bent trailing edge of the sheet metal is momentarily stopped between the two dies, and the pneumatic cylinders are actuated to reshape the trailing edge. This arrangement requires a completely separate and relatively complex mechanism that serves no other purpose but to dekink the edges of the material.
From the above, it can be appreciated that uncoiling systems of the prior art are not fully optimized to provide a consistent height of a material payoff line, to accommodate heavy coils of thin gauge material, or to dekink heavy gauge material. Therefore, what is needed is a novel apparatus incorporating a vertically traversing reel-type uncoiler and a dekinker cooperating with the uncoiler, and a related method.
According to the present invention, there is provided an apparatus and method for uncoiling a coil of web material and dekinking the leading and trailing edges of the web material. The apparatus includes a unique uncoiler, a unique dekinker, and a conventional feeder. The apparatus conveys material paid off from a coil of the material to a machine downstream of the apparatus. The feeder is positioned downstream, includes pinch rolls for pulling the material through the feeder, and also includes straightener rolls for working and straightening the material therebetween. The dekinker is positioned just upstream of the feeder and includes a threader roll and a breaker roll positioned below the threader roll. The threader and breaker rolls are independently displaceable with respect to one another to compress and straighten out a kinked length of the material therebetween. The uncoiler is positioned just upstream of the dekinker and includes a mandrel extending through an inside diameter of the coil. A displacement apparatus is mounted to the mandrel for vertically displacing the mandrel to control the height at which the material is paid off from the coil.
In another aspect of the present invention, there is provided a method of conveying material from a coil to a machine downstream. The method includes uncoiling the coil of material by supporting the coil from an inside diameter thereof and vertically displacing the coil as the outside diameter of the coil decreases as the material is paid off therefrom. Thus, the method controls the height at which the material is paid off from the coil. The method further includes dekinking a kinked portion of the material by compressing the kinked trailing end between independently moveable upper and lower rolls.
It is an object of the present invention to provide a material handling system having an uncoiler with a vertically adjustable mandrel rotatably mounted to a horizontally traversing carriage and having a payoff roll that cooperates with the mandrel to maintain a common payoff height of web material from a coil, regardless of the changing outside diameter of the coil, and within a certain vertical range. In this way, it is possible to easily center a coil along a material flow path through a feeder, to maintain a consistent angle of material flow from the uncoiler to a downstream device, and to minimize coil break of the web material.
It is another object to provide an uncoiler having an expandable mandrel for spearing an inside diameter of a coil of web material that enables uncoiling of heavy coils of light gauge stock, and thus eliminates the defect of a xe2x80x9cwavy edgexe2x80x9d of web material.
It is still another object to provide a reel-type uncoiler that eliminates the problems associated with side plates of a cradle-type uncoiler such as the need to precisely center the coil between the side plates, damage to side edges of the coil, binding of the coil between the side plates, and slivers generated from side edges of the coil abrading the side plates.
It is yet another object to provide a reel-type uncoiler that cooperates with a payoff roll to synchronize payoff of web material from a coil and to reduce slack conditions of web material being paid off from the coil.
It is a further object to provide a reel-type uncoiler that requires less floor space than prior art reel-type uncoilers and eliminates the typical material loop between prior art uncoilers and a downstream device.
It is still a further object to provide a material handling system that incorporates a dekinker for easy threading of a leading end of web material from a coil of web material to a downstream feeder.
It is yet a further object to provide a material handling system that incorporates a dekinker that eliminates kinks at the trailing ends or near the trailing edge of web material to wipe a kink flat and prevent double thicknesses of the web material from entering a feeder.
It is an additional object to provide low cost, efficient reel-type uncoiling apparatus that enables automation of web-type material handling, that requires less floor space than prior art reel-type uncoilers, and that does not require use of a pit to accommodate the apparatus.
It is yet an additional object to provide methods of conveying, dekinking, and handling a coil of web material in a manner consistent with the above-mentioned objects.